巴基斯坦毛刺线虫在苹果园的发生及其与树势的关系

Occurrence of Trichodorus in apple orchards and its relation to growth visor of trees

研究表明，导致北京南口农场苹果短粗丛根病的巴基斯坦毛刺线虫（Ｔｒｉｃｈｏｄｏｒｕｓ ｐａｋｉｓｔａｎｅｎｓｉｓ）在所调 查的４５个果区中的３１个果区大量发生，总样品频率和最高群体密度分别为 ４７． １％和 ５３６条／２００ｍｌ土壤。各 区平均群体密度在１～２８２条／２００ｍｌ土壤之间，以第４０区的密度最高。线虫群体在３～５月间数量很少，６～ ７月大量发生，８～９月开始下降。弱树根围群体数量最多，达５２０条／２００１ｍｌ土壤，半死树次之，旺树和死树 根围线虫数量最少，分别为 ６４条／２００ｍｌ土壤和 ８０条／２００ｍｌ土壤。

Trichodorus pakistanensis Siddiqi, causing serious stubby-root disease in apple ires on Nankou Farm of Beijing, occurred extensively in 31 out of 45 investigated apple orchards. The frequency of samples con- taining nematodes was 47.1 %, and the highest nuber of nematodes in a sample was up to 536 per 200ml soil sample, with an average population density among diffirent orchards to be varied from 1 to 282 nemetodes The nematode population had an obvious seasonal change pattern: eging very low in March,April and May,and be- coming high in July, but bogining to tall in August and September. The growth vigor of apple trees was in close relation to the nematode population. The rhizospohere of weak trees was always inhabitated by nematodes at a pop- ulation density of 520 heads per 200ml soil sample on average, but that of half-dead, entirely dead and healthy ires contained 208, 80, and 64 nematodes per 200ml soil sampe,respectively.